Two Cassegrain telescopes were constructed to function as sender and receiver for an FTIR spectrometer primarily for the purpose of obtaining spectral data for analysis of military night vision emission targets, and spectral calibration of external variable temperature thermal radiation sources, utilizing freezing-point type blackbodies for primary radiation temperature standards. The sender and receiver telescopes, F/7 and F/5, respectively, each employ 0.30 m (12 in) diameter primary and 0.15 m (6 in) diameter secondary, protected Ag coated Zerodur mirrors. In operation, a thermal target image formed by the sender, whose optical axis is aligned with that of the receiver and spectrometer, is transmitted to and brought to a focus at the spectrometer entrance aperture by the receiver telescope. With (lambda) /8 p-v optical surface accuracy at 633 nm, telescope system tests indicate near diffraction- limited performance in the visible, and 2.81 mrad (full) FOV with further reduction achieved with field stops. Wavelength range capability of the commercially available FTIR instrument employed is approximately 0.22 micrometers (55000 cm<SUP>-1</SUP>) to 22 micrometers (450 cm<SUP>-1</SUP>) with wavenumber resolution of about 0.013 cm<SUP>-1</SUP> in the IR to 0.769 micrometers (13000 cm<SUP>-1</SUP>). In this paper, the techniques and tests employed for the telescope mirror construction are described. An innovative technique for secondary alignment for Hindle's tests of a Cassegrain utilizing a He-Ne laser is presented. Telescope mountings for positioning and alignment with the FTIR are briefly discussed, as well as radiometric and calibration parameters for the integrated system.
This paper describes the design of test equipment constructed to enable the Marine Corps Logistics Base the capability to provide the required optical/IR boresight and electronic tests for rebuild and TOSH (TOW optical sight hardening) modification for the TOW (tube launched, optically tracked, wire guided) guided missile launcher optical/infrared sight. Optical modification and calibration are performed to improve system accuracy and reliability against failure, especially in a battlefield environment. Although principle concern was for the day sight, provision for the thermal night sight was also included. This design includes a large diameter optical beam, provision for thermal targets and night sight boresight alignment capability with the day sight. Primarily, a specially constructed collimator test set is discussed, implemented as the TOW 150 test and alignment station. In addition, a precision TOSH prism test system is briefly described, which is used to facilitate internal optical component boresight alignment utilizing a HeNe laser, alignment telescope and video camera. Radiometric theory is applied to the collimator geometry, which includes the modulation factor, Planck radiation function and appropriate bandpass integrated to yield effective rms irradiance values for calibration of the day sight.